Fixing Marantz 1060 power amp - Right channel

[Homer4beer]

Hi all,

Following on from my other thread (http://audiokarma.org/forums/index....aps-on-marantz-1060-can-i-use-np-caps.770598/) I'm now going about fixing the right channel of the power amp.

It was going beautifully until the right channel got some pretty decent hum in it and a big volume increase.

I now need to have the balance at the 8:30 position to be in balance.

Hum starting to become quite annoying when listening at lower levels. Still present using headphones.

where to begin. you'll need the service manual and the circuit diagram.

I would start with measuring voltages, once the hum/loudness starts
(based on an assumption that when cold, everything is normal) you
can compare the right channel to the left channel. and note
any differences you find with the values on the circuit diagram and
any notations in the service manual.

you can skip a lot if you can determine where the signal goes bad.

1. if the preamp section is mechanically connected to the power amp
side, then swap preamp output signals. if it stays in the right then
you can eliminate the preamp sections as the cause.

The music you hear after it is off is just coming from the main filter caps draining since it is a cap coupled amp. As was mentioned before, look at the back of the amp for the jumpers that connect the preamp to the amp. Swap the jumpers so that the left preamp is going to the right amp and right preamp is going to the left amp. If the problem switches the the other channel, then you know the issue is in the preamp. If the problem stays in the same channel as before, you can pretty confidently assume the issue is in that channels driver section.

Since the 1060 uses those little plastic jumpers if original, you may have to get some other RCA interconnects that are long/flexible enough to route the preamp to the opposite amp channels.

Ok it seems the pre amp is fine. It's something on the right power amp.

Next step is? (Pulling the power amp apart completely)?

 

[Homer4beer]

Ok board is out.
Can anybody see any possible issues here?

Is there a list of parts to order for this board for a restore?

 

[Bob]

excellent - you've narrowed it down to one board/output/channel.

now get the schematic. get your DMM/VOM out, two leads attached, clips at the
end of each probe. TURN OFF power and attach, turn on power and read the
measurement. turn power off.

note on schematic what the value is. USE RED. then compare to the value on
the schematic. measure other channel if needed.

you are measuring the voltages.

if you skip the procedure and some/all of the components go from OK&working
to unknown then you must then use a dim bulb on your input AC supply
to prevent further/complete destruction.

you should be able to measure all of the voltages in one evening. do what the pilots
are required to do by law - no alcohol in last 24 hours before you start. to prevent
shaking hands short-circuiting everything in your postal code. and dimming the
lights in your entire province and possibly all of Oz. (I love Oz).

then post results here and note anomalies. my guess is a failed active component
and potential sub-optimal passives around it.

before you start. unplug and firmly plug in all internal cables. work ALL the
externally available switches to ensure its not loose dentures. guarantee
no external problems in external connections include source, cables, grounds,
and speakers.

good luck

 

[Homer4beer]

Well that's going to be a bit harder now the board is out......

Should I put it back in or just use alligator clips to rewire it on the bench?

 

[Bob]

if the board is out, are you comfortable with checking the output devices in pix1?

the goal is to remove them, test them using a VOM/DMM with a transistor
tester. if all are good, (probably since you do have good sound - its not
like a dead channel.) Your biggest problem is re-assembling them properly:
cleaned off mica insulators (or use new ones), re-greasing them with
non-conductive grease, remount being SUPER careful about potentially
shorting the entire set. if you haven't done this before then don't practice
on this unit.

Or assume the outputs are good, then one-by one unsolder the transistors
and test them. after testing, re-solder with clamps on all leads to draw off the
heat. mark the device's orientation on board, schematic, and device to
prevent re-installing them backwards. and if there's stenciling on the board
for transistor - ensure that's its correct in case you miss one or two of the
above points. you are looking for semi-circles and EBC markings - this is
your only hope of getting back to normal. if you destroy a transistor
you will have to reverse engineer the original transistor's electrical specifications
to find a suitable (perhaps not optimal) replacement.

Unless you have done similar I would not clip it back into operation. I've
done this using a different color wire for each connection, stickon mini-labels
at four places: board1 location, wire 1 at board1 location, board2, wire at board2, etc.
not alligator clips with mile long exposed metal that shorts everything it touches
but spring-loaded clips that are completely insulated even from lying directly on
live traces.

I think you will find a testing solution you can be comfortable with. However,
I think you need the dim bulb tester NOW. there are way too many opportunities
for misadventure. one slip or one mistake will damage it further and introduce
more issues.

 

[willyrover]

My 1060 had a hum/loud channel issue. One of the circled caps was bad. Can't remember which one but I think it tested ok on ESR when in circuit but literally fell apart when I unsolder it.

Check these caps on your loud channel.

 

[Bob]

@willyrover great input.

 

[Homer4beer]

Or assume the outputs are good, then one-by one unsolder the transistors
and test them. after testing, re-solder with clamps on all leads to draw off the
heat. mark the device's orientation on board, schematic, and device to
prevent re-installing them backwards. and if there's stenciling on the board
for transistor - ensure that's its correct in case you miss one or two of the
above points. you are looking for semi-circles and EBC markings - this is
your only hope of getting back to normal.


I think you will find a testing solution you can be comfortable with. However,
I think you need the dim bulb tester NOW. there are way too many opportunities
for misadventure. one slip or one mistake will damage it further and introduce
more issues.

Fantastic advice! Thanks Bob. I think I'll try with the caps first and then the transistors. I have a multi meter only at this stage however I'm looking to buy this ESR tester.

http://www.ebay.com.au/itm/201750333467

What caps should I use?

Cheers guys

 

[Homer4beer]

My 1060 had a hum/loud channel issue. One of the circled caps was bad. Can't remember which one but I think it tested ok on ESR when in circuit but literally fell apart when I unsolder it.

Check these caps on your loud channel.View attachment 1009970

Thanks mate.

What caps did u use when replacing these?

 

[willyrover]

Thanks mate.

What caps did u use when replacing these?

Nichicon MUSE..KZ series.

 

[Homer4beer]

I think I've found the problem

At this stage I'm just going to replace these with what I can find just to get it running again and order the required components to do a full recap of the amp when I'm on holidays (2 weeks time).

 

[willyrover]

Yup...same thing happened on my 1060. Leads just pulled right out.

 

[Bob]

great! recap these then do the others.

do burn the unit in - in spite of what the burn-in deniers say, the caps will thank you,
the music will thank you, and your ears will thank you.

 

[Homer4beer]

great! recap these then do the others.

do burn the unit in - in spite of what the burn-in deniers say, the caps will thank you,
the music will thank you, and your ears will thank you.

How do you "burn in"?

Back of the board has been cleaned up and all caps replaced with Jaycar specials (total cost $5 Aus). I'll replace them all again with better ones soon.

Solder job not too bad for an amateur

Now to reassemble and see if that was the issue!

 

[Bert 1100]

Looking good !
These same blue / light purple caps seem to have this problem of corroding legs very often, across many makes...

 

[Homer4beer]

Wooohoo!

IT LIVES!

 

[Homer4beer]

Guys it is absolutely SILENT now in terms of noise. Perfect balance left and right, I'm absolutely over the moon

Thank you all for your amazingly generous input and for taking the time out to help with my rather simple issues and novice questions.

Cheers!
Homer

 

[Bert 1100]

Woohoo ! Well done
And a question : how come that last photo is of such high resolution ?
The photos I upload directly always seem to be resized down....

 

[Bert 1100]

Oh, and if you will be taking the board out again, careful with the bias diodes (on the heatsink, wired to the board) their leads are quite fragile and often break off right at the diode body...

 

[Homer4beer]

Woohoo ! Well done
And a question : how come that last photo is of such high resolution ?
The photos I upload directly always seem to be resized down....

Thanks Bert

Regarding the pic sizes I've just been resizing the pics to about 500Kb in Adobe Lightroom. If a pic can remain bigger at the same file size Lightroom will allow it I suppose.